318 



COMPARATIVE ZOOLOGY. 



Proteus of Austria, Menobranchus of tlie eastern United 

 States, and the two-legged Mud-eel (Siren) of South Car- 

 olina. Others drop their gills, and always have four limbs, 

 as the aquatic Newts and land Salamanders. 1 " The fore 

 limbs first make their appearance in the tadpole. 



2. Labyrinthodontia, now extinct, resembled gigantic 

 Salamanders, except in their complex teeth and exoskele- 

 ton of bony plates. 



3. Ccecilia have neither tail nor limbs, a snake-like form, 



FIG. 296. Proteus anguinus. Europe. 



minute scales in the skin, and well-developed ribs. They 



are confined to the tropics. 



4. Batrachia include all the well-known tailless Am- 

 phibians, as Frogs 

 and Toads. They 

 have a moist, naked 

 skin, ten vertebrae, 

 and no ribs. As they 

 breathe by swallow- 

 ing the air, they can 



be suffocated by holding the mouth open. They have 



Fio. 296. Red Salamander (Paeudotriton ruber). 

 United States. 



